Add badges for the Debian packages

[mr-c]

• Is any new functionality in tested? (This can be checked with
  make clean diff-cover or the CodeCov report that is automatically
  generated following a successful CI build.)
• Was a spellchecker run on the source code and documentation after
  changes were made?
• Have any changes to the command-line interface been explicitly described?
  Only backwards-compatible additions are allowed without a major version
  increment. Changing file formats also requires a major version number
  increment.
• Have any substantial changes been documented in CHANGELOG.md? See
  keepachangelog for more details.
• Do the changes respect streaming I/O? (Are they tested for streaming I/O?)